EL DORADO — Officials are trying to identify an unknown liquid that has turned a creek in southern Arkansas bright green.

The El Dorado News-Times reported that city and Union County officials worked all day Tuesday to contain the contamination that was first reported in the early morning. They used dump trucks and front-end loaders to dam the creek with gravel.

El Dorado utilities manager Mark Smith said the mystery liquid ran along the railroad tracks near East Main Street and flowed north into a creek toward the county fairgrounds.

He said officials have sent samples off for testing and hope to know the results by Wednesday. The Arkansas Department of Environmental Quality was notified.